1. Field of the Invention
The present invention relates to a method and apparatus for connecting and disconnecting threaded tubulars to or from a tubular string in a wellbore.
2. Background of the Related Art
The process of drilling and installing casing in a wellbore requires the connection or makeup of many sections of tubulars, such as drill pipe or casing. These sections of tubulars may be individual joints or stands of multiple joints. As a wellbore deepens, more tubulars must be threadably connected onto the string. Consequently, the process of threadably connecting tubulars is an important part of wellbore operations and utilizes a significant amount of time and equipment. Furthermore, a tubular string may need to be removed from the wellbore for a variety of reasons, such as replacing a drill bit or due to cross-threading of casing. Accordingly, disconnection or break out of many tubular sections is also an important part of wellbore operations.
In order to improve the quality of threaded connections and make efficient use of expensive rig equipment, many different power tongs have been developed. For example, U.S. Pat. No. 5,386,746 discloses an apparatus for making and breaking wellbore tubulars that includes a frame supporting up to three power jaws aligned vertically with respect to each other. The middle set of power jaws is reverse oriented to the upper and lower sets of power jaws and cooperates with either the upper set or the lower set to effect torquing.
U.S. Pat. No. 6,634,259 discloses a power tong having a plurality of power jaws and a power spinner for spinning wellbore tubulars. The power spinner spins a tubular at a relatively high speed but at a relatively low torque while holding another tubular fixed with one of the power jaws. The spin process continues until the two threaded tubulars shoulder up, e.g. until a pin shoulder engages the box shoulder. After shouldering up, the power spinner is stopped and two of the power jaws are used to apply high torque to the connection or joint in a well known manner so that the joint is securely fastened and sealed. The application of high torque continues to rotate the tubulars with respect to each other but at a very low speed or rotation. However, once the tubulars are shouldered, only a small amount of further rotation is necessary to complete the connection. Likewise, when breaking out joints, two power jaws apply a high torque to initially break the connection. Then the power spinner spins one tubular with respect to another tubular held by a power jaw until the threaded connection is completely disconnected. In this manner, the connection can be quickly made or broken to save considerable time and money while drilling a well.
What is needed is an apparatus that can both spin a tubular to establish a threaded connection and apply a final torque value to the threaded connection. It would be desirable to have such an apparatus that was simpler and took less space.